This application claims the priority of 198 32 625.4-41, filed Jul. 21, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a method for making a stacked reactor for the production of hydrogen from hydrocarbons from a plurality of catalyst disks stacked one on the other, as well as a catalyst disk especially suited for making such a stacked reactor.
German Patent Application 197 43 673.0 of the same assignee as the present application discloses such a stacked reactor formed from catalyst disks stacked one on the other. To make the stacked reactor, a thin and greatly compressed layer forming a body (catalyst disk) is formed from at least one catalyst powder by pressing, with copper powder, especially dendritic copper, being added to the catalyst powder. After compression the body is subjected to sintering, and then the individual catalyst disks are stacked one on the other and bonded to form a stacked reactor. In bonding together the individual catalyst disks, care must be taken to achieve a tight formation of the joints between the individual catalyst disks. In high-density ceramics, cementing, welding, soldering and clamping are known as joining methods. In the present case of a porous catalyst disk, these known joining methods can be only partially used.
In DE-OS 25 07 937 a tubular cleaving furnace with disk-shaped catalyst material is disclosed. The catalyst disks are carried centered on a support tube and have in the center a boss of greater thickness.
The invention addresses the problem of providing a method for making a stacked reactor which will permit an especially simple and low-cost production of a compactly built stacked reactor in which the active volume of the catalyst disks is not, or is but slightly, reduced and an especially tight configuration of the joints will be achieved. The invention is furthermore addressed to the problem of preparing a corresponding stacked reactor.
For the solution to this problem, a method is achieved according to the invention for making a stacked reactor in which sintering of the catalyst disks all together takes place in the stacked condition, as well as a stacked reactor for hydrogen production from hydrocarbons made from at least two catalyst disks produced by pressing catalyst material and sintered in the stacked condition. Accordingly, a sintering of the catalyst disks is performed in the green compact state, i.e., after the pressing, first all together in the stacked state. By the common sintering a tight joining of the individual catalyst disks is achieved. Because the sintering of all catalyst disks is performed together, and no longer individually, as in the prior art, working procedures can be eliminated, so that the method of the invention can be performed more simply and inexpensively.
In a currently contemplated embodiment of the invention, the sintering of the catalyst disks is performed by a predetermined application of pressure. By this compression sintering, an especially good bonding of the catalyst disks is achieved. Advantageously, the pressure application is sustained throughout the entire sintering process.
The predetermined application of pressure to the catalyst disks during sintering amounts advantageously to between 2 and 20 N/mm2, preferably between 5 and 15 N/mm2.
A catalyst disk for the construction of a stacked reactor according to the invention has projections in the area of contact with an adjacent catalyst disk for the formation of joints. When the catalyst disks are stacked in the green compact state, they no longer lie flat on one another but stand on one another at the projections formed circumferentially or interruptedly. This configuration makes it possible to form hollow spaces between the individual catalyst disks serving, for example, as channels. Since the pressure under which the catalyst disks lie one on the other is now no longer applied to the entire surface but only to the projections, an improved quality is achieved in the joint between the catalyst disks after sintering.
In an especially advantageous embodiment of the invention, hollow spaces, such as distribution and collection channels formed in the catalyst disk or by two adjacent catalyst disks, have a system for supporting the hollow spaces. Thereby, deformation of the catalyst disk or disks during the sintering is prevented.
In one embodiment of the invention, the support system is a copper grid, which is advantageously covered at least partially by a metal plate. In another, preferred embodiment of the invention, the support system of support consists of bars pressed onto the catalyst disk. In this manner the design is simplified and the cost of manufacture is minimized, since separate parts no longer need to be inserted into or between the catalyst disks.